1. Field of the Invention
The present invention relates to a yarn piecing method and a yarn piecing apparatus used in textile machines such as open-ended spun yarn spinning machines, and fasciated spun yarn spinning machines and in which a spun yarn spun by and delivered from a yarn forming means and another yarn withdrawn from a yarn package on which the spun yarn is wound are pieced to each other.
2. Description of the Related Arts
Generally speaking, textile machines such as open-ended spun yarn spinning machines or fasciated spun yarn spinning machines include a drafting means, a yarn forming means, a yarn taking-up means, a yarn winding means, and the like. When staple fiber bundles are supplied, a spun yarn such as, a fasciated spun yarn is spun in the yarn forming means and then wound on a yarn package by the yarn winding means.
When a yarn breaks in the yarn producing process, a yarn piecing operation is usually carried out. Namely, the yarn piecing operation includes the steps of stopping a yarn winding means, sucking a spun yarn delivered from a yarn forming means (referred to as a first yarn hereafter) by a first yarn sucking means provided on a yarn piecing apparatus; withdrawing a yarn from a yarn package (referred to as a second yarn hereafter) by a second yarn sucking means; and piecing the first and second yarn to each other by carrying the two yarns to a yarn piecing means.
In this conventional yarn piecing method, a yarn spun by and delivered from a yarn forming means during a yarn piecing operation is sucked and stored in a yarn storing means provided between a yarn taking up means and the yarn piecing means. Then, when the yarn piecing operation is completed, the non-rotated yarn package is restarted to rotate in such a way that the rotational speed thereof is rapidly increased with a predetermined acceleration to take out the yarn stored in the yarn storing means. Thereafter, the rotational speed of the yarn package is changed to a predetermined yarn winding speed to wind up a spun yarn delivered from the yarn forming means.
In this conventional yarn piecing method however, since the rotational speed of the package is increasingly accelerated after the yarn piecing operation is completed, it is required that the total length of the yarn, i.e., the sum of the length of the yarn stored in the yarn storing means when the yarn piecing operation is carried out and the length of the yarn produced during a time from when the yarn package is not rotated to when the rotational speed of the yarn package reaches a predetermined winding speed, (usually requiring 0.5 to 1 second), be sucked and stored in the yarn storing means. Thus, in the conventional method, a yarn storing means having a large yarn storing capacity is necessary.
On the other hand, when such a large capacity yarn storing means is provided on a machine frame, it must be formed in a configuration such that the yarn sucking path is folded several times as shown in Japanese Unexamined Patent Publication (Kokai) No. 53-134943, making it difficult to make such a yarn sucking means.
When a yarn piecing operation is carried out utilizing a knotter, the time required to piece yarns is very short, for example, 0.1 to 0.3 second, therefore, the yarn can be sufficiently stored in the yarn storing means without providing a yarn storing means having a relatively longer length. When a yarn piecing operation is carried out utilizing a splicer, however, the time required for piecing yarns is usually 0.4 to 0.7 second, longer than the previous method. Accordingly, the amount of yarn stored in the yarn storing means is increased.
Therefore, a yarn storing means having an extremely large capacity for storing yarn is required to be provided when intending to store the yarn produced during the time in which the rotational speed of the yarn package reaches a predetermined yarn winding speed from a non-rotated condition and the yarn produced during the yarn piecing operation.
However, it is very difficult to make a yarn storing means having such a large capacity, and it is also very difficult to find a place on a textile machine on which such a large capacity yarn storing means may be mounted. Thus, it is impossible to use this kind of yarn storing means in actual production.
Further, since yarn existing between the yarn piecing means and the yarn package cannot be wound on the yarn package under a predetermined yarn tension simultaneously with completion of the yarn piecing operation, a snarling naturally occurs in the yarn in the yarn piecing means and therefor a problem arises in that snarls are easily wound onto the yarn package with a normal spun yarn.